Apparatus for dishing and perforating sheet metal



y 1934- H. s. HASSELQUIST 1,959,101

APPARATUS FOR DISHING AND PERFORATING SHEET METAL Filed May 29, 1930 INVENTOR. Hugo 5. Haws/ 141152 /fZW 5AM A TTORNE Y.

Patented May 15, 1934 UNITED STATES PATENT orrica APPARATUS FOR DISHING AND PERFORAT- ING SHEET METAL Application May 29, 1930, Serial No. 457,033

4 Claims.

This invention relates to an apparatus for dishing and perforating sheet metal.

More particularly, the object of the invention is to provide for forming a perforation in a sheet of metal in a single operation, the side walls of the perforation being substantially perpendicular to the normal plane of the sheet and parallel to the axis of the perforation, while the metal surrounding the perforation is dished and displaced laterally to one side of the sheet.

Another object of the invention is to provide complementary die members adapted to form a perforated embossment in sheet material.

The invention has been found to be particularly useful in producing the non-circular perforations employed in Pat. 1,705,463 to B. T. Andren for attaching metal parts, wherein a nut is attached to a sheet of metal by passing a short non-circular shank on said nut through a correspondingly shaped perforation, the metal surrounding the perforation being raised to lift the nut above the normal plane of the sheet, and the nut is clinched in the sheet by upsetting the edge of the shank. In this case the non-circular perforation in the embossment holds the nut from turning while the embossment functionsas a spring washer when strained by tightening of the nut.

One embodiment of this invention is set forth in the accompanying drawing, in which,

Fig. 1 is a perspective view of the punch and die.

Fig. 2 is an elevation, partly in section, of the punch and die at the position of engaging with a sheet of metal previous to dishing it.

Fig. 3 is a similar view upon the completion of the dishing operation, the lower part of punch also being shown in section.

Fig. 4 is a view similar to Fig. 3 after the sheet has been perforated.

Fig. 5 is a view of the die members in which the punch has a modified form of protuberance on its tip, and

Fig. 6 is a perspective view of a sheet of metal that has been dished and perforated according to the invention.

The apparatus, in its preferred form, comprises a pair of cooperating complementary male and female die members, indicated on the drawing by the figures 1 and 2 respectively.

The male die member or punch 1 comprises a shank 3 of suitable form, a conical protuberance or projection 4 at the end thereof, and a shearing edge 5 formed by the juncture of the protuberance or projection 4 with the sides of the shank 3.

The female die member 2 comprises an upper surface 6 adapted to engage with a sheet of metal,

an aperture 7 complementary to the punch 1 and cooperating with it to perforate a sheet of metal, a dished depression 8 surrounding said aperture on the side facing the punch and sloping in funnel form from the surface 6 of the die down to the opening of the aperture '1, and shearing edge 9 formed by the juncture of the surface of said depression 8 with the side walls of the aperture '7.

In addition the apparatus may be provided with a suitable device not shown to strip the sheet of metal from the punch on the return stroke of the latter.

In operation, a sheet 10 of metal or other workable material is positioned on the die 2. The punch 1 is then moved downwardly toward the die, forcing a part of the sheet 10 into the dished depression 8, and stretching it beyond its elastic limit so that it is permanently displaced downwardly as shown in Fig. 3. This produces an embossment on the under side of the sheet, and a corresponding hollow or concavity on the upper side. Further movement causes the punch to blank out the slug 11 from the center of the embossment, pushing it past the cutting edge 9 of the female die and down through the aperture 7. In this way a perforation 12 is formed in the sheet of metal, with the metal 13 surrounding said perforation dished or displaced downwardly with respect to the sheet as shown in Fig. 4.

When the punch 1 is withdrawn, the displaced metal 13 surrounding the perforation 12 may spring back slightly. Thus with certain steels if the displaced metal 13, while under pressure in the die makes an angle of 13 with the adjacent unbent sheet metal, the angle to which it will spring back after the punch is withdrawn may be about 10. The angle which the surface of the dished depression 8 should make with the die surface 6 in order to allow for this resiliency in the metal can readily be determined by simple tests to secure the ultimate angle desired with any particular specification of sheet and configuration of embossment and perforation. In the case of irregular embossments, this angle may not be uniform on all sides of the perforatlon and in case of non-circular perforations the angle of the depression 8 may be different on different sides of the aperture 6 in order to provide a uniform angle for the embossment.

The dishing of the die surface 8 facilitates centering of the punch so that upon completing the dishing operation, the punch will be positioned directly over the aperture 7 of the cutting die 2.

One important result of this method of dishing and perforating a sheet is that the side walls 14 of the perforation 12 are substantially parallel to the axis of the perforation and perpendicular to the normal plane of the sheet 10. This provides a maximum bearing surface for the member which is inserted through the perforation and held therein.

Fig. 5 illustrates a modification in which the protuberance appears as a mound shaped bulge 15, the surface of the bulge flattening out where it joins the shank 3 of the punch to form a substantially right angled shearing edge 5. In order to less'en wear on the shearing edge 5 the bulge 15 should be high enough so that the sheet of metal 10 is dished to the bottom of the depression 8 before the cutting edge 5 engages with the sheet.

The invention may have various modifications within the scope of the accompanying claims.

I claim:

1. An apparatus for dishing and perforating a sheet of metal in one operation, comprising a pair of complementary male and female die members adapted to cooperate to perforate the sheet of metal, said male die member having a conical tip extending forwardly from the cutting edge and said female die member having a recess or depression with frusto-conical sides surrounding the die opening adapted to receive the sheet metal at the time of perforating the same to thereby form an embossment in the sheet of metal adjacent the perforation.

2. Apparatus for embossing and perforating sheet material comprising complementary die members, the lower die member having a depression in its upper face conforming to the embossment it is desired to make, and an opening for receiving the upper die member, the upper die member being of the proper size and shape to make the perforation desired and having a projection on its leading end for seating the sheet in the depression in the lower die member before the cutting operation is started.

3. Apparatus for embossing and perforating sheet material comprising complementary die members, the lower member having a depression in its upper face conforming to the embossment it is desired to make, and an opening for receiving the die member, the upper die member being of the proper size and shape to make the perforation desired and having cutting edges, and a projection on the leading end of the upper die member extending beyond the cutting edges for seating the sheet of material in the depression in the lower die member before it is engaged by the cutting edges.

4. Apparatus for embossing and perforating sheet material comprising complementary die members, the lower die member having a depression in its upper face conforming to the embossment it is desired to make and an opening for receiving the upper die member, the upper die member being of the proper size and shape to make the perforation desired and having a projection on its leading end which conforms substantially in contour to the depression in the lower die member to seat the sheet in the depression in the lower die member before the cutting operation is started.

HUGO S. HASSELQUIST. 

